Abrading apparatus



June 1939- w. A. ROSENBERGER 2,163,631

ABRADING APPARATUS Filed Dec. 9, 1956 Patented June 27, 1939 UNITED STATES ABRADING APPARATUS William A. Rosenberger, Hagerstown, Md., as-

signor to Pangborn Corporation, Hagerstown, Md., a corporation of Maryland Application December 9, 1936, Serial No. 115,047

Claims.

The present invention relates to abrading apparatus and it is more particularly concerned with mechanical abrasive projecting or propelling machines wherein an abrasive is projected against 5 the work by centrifugal action.

It is a primary object of this invention to provide an abrading machine having all of the desirable characteristics of the successful abrading machine disclosed in patent to Keefer No.

2,108,005, dated Feb. 8, 1.938, and marketed under the trade-name Rotoblast together with further highly desirable structural and operating features which materially improve the life and efficiency of the mechanism.

It has been found that when comparatively large shot is used as the abrading medium in the machine shown in the aforementioned patent some of the shot strikes the work and ricochets back into the wheel, with the result that it is struck by the blades with an impact of considerable magnitude. The blades are made of a comparatively hard alloy so as to resist wear and are therefore somewhat brittle and they often break when the shot ricochets back into the wheel. 5 The blade fragments thrown from the wheel often ricochet from the work on the machine housing back into the blades and, by reason of the terrific impacts involved with the greater masses, the blade assembly is often completely destroyed.

It is accordingly the major object of the invention to provide the wheels of abrading machines with means for preventing the blades from striking abrasive or blade fragments rebounding back into the wheel.

A further important object is to provide a novel blade guard construction for abrading wheels which will protect the blades against impact with abrasive rebounding into the wheel and which will allow the blades to be readily removed and 40 will not impair the accessibility of the parts for servicing. Y

It is another object to devise novel blade protecting guards for abrading wheels which will adequately protect the blade surfaces against 45 abrasive or other material entering the periphery of the wheel and which will also materially reduce the power input by reducing the windage loss in the machine.

A further object is to devise a novel blade lock- 50 ing assembly for the blades of abrading machines which will securely hold the blades in place while the machine is in operation and yet will readily permit the blades to be removed when desired.

Further objects of the invention will become 55 apparent as the description thereof proceeds in connection with the annexed drawing, and from the appended claims.

In the drawing:

Figure 1 is a fragmental face view of an abrasive throwing wheel embodying the present Ii! invention and parts thereof have been broken away in order to more clearly illustrate the structure involved.

Figure 2 is a fragmental sectional view taken on the line 2-2 of Figure 1, looking in the direc- 10' tion of the arrows. 4

Figure 3 is a fragmental elevational edge view of the wheel assembly shown in Figure 1 and illustrates one of the blades mounted in the wheel and locked in place thereon. V

Figure 4 is a fragmental sectional view taken substantially on the line 4-4 of Figure 1 illustrating the parts as they appear when viewed in the direction of the arrows.

Figure 5 is a vertical sectional view of an 20 abrading machine embodying a modification of the invention.

Figure 6 is an isometric view of the unitary blade guard construction shown in Figure 5.

Figure 7 is a fragmental elevational view of a 5 further modification of the invention and is somewhat similar to that shown in Figures 1 to 4, inclusive.

Figures 8, 9 and 10 are views similar to Figure '7 or still further modified forms of the invention. 30

Figure 11 is a view similar to Figures 8, 9 and 10, but illustrates a further modification of the V invention somewhat similar to Figure 1 but employing a self-draining guard.

With continued reference to the drawing, 5 wherein similar reference characters have been employed to designate like parts throughout the several views thereof, the abrading wheel per se forms the subject matter of the aforementioned patent and will accordingly only be described in 40 suflicient detail herein to facilitate an understanding of the blade guard constructions of the present invention.

The wheel comprises a rotor l0 mounted on a shaft journalled for rotation in any desired manner (not shown) and carries a plurality of abrasive throwing blades ll. Also secured to rotor I0 is an impeller I2 having impelling vanes l3. Mounted in the space between the impelling vanes 13 and the propelling blades II is a cylindrical cage l4 having a single outlet opening l5. Abrasive is fed to the interior of cage l4 and it is picked up by vanes l3 andejected through openings 15 onto the inner 'ends of propelling blades II.

In view of the fact that the impelling vanes are preferably equal in number to the propelling blades and the impelling blades are preferably advanced with respect to the propelling blades, the abrasive is fed through opening I 5 in timed relationship to the propelling blades so as to insure each blade ll receiving a full charge of abrasive as it passes opening I5. The abrasive introduced over the inner ends of blades H is picked up with small impact and is slid outwardly over the propelling surfaces of the blade under the influence of centrifugal force and discharged at high velocity from the tips of the blades in a direction determined by the radial velocity of the abrasive and the tangential velocity of the blade tips.

In view of the fact that the abrasive is fed to the inner ends of the blades at a limited region, the abrasive discharges from the wheel in a predetermined direction and hence has directional control. With the cage adjusted as shown to discharge the abrasive upwardly over the inner ends of the blades, the work is placed under the wheel as the wheel discharges at this point.

As previously mentioned, the abrasive rebounding from the work tends to reenter the wheel and in order to prevent this from taking place in the form of invention shown in Figures 1 to 4 inclusive, I mount a guard of curved configuration between each pair of blades so that rebounding abrasive cannot enter the spaces between the blades. Although this guard may assume various forms, and may be associated with the wheel parts in various ways, I have in Figures 1 to 4, inclusive shown a guard that is integrally formed with the dove-tail plates which define the blade guideways.

With continued reference to these figures, a plurality of sector-shaped plates I! are secured in spaced relationship to each other to rotor ID by means of a plurality of screws it. In order to assist screws [8 in restraining plates I! against outward movement in response to centrifugal force, rotor i0 is provided with an inwardly facing abutment l9 with which a corresponding abutment 2| on each plate I1 is adapted to cooperate.

The neighboring faces of plates H are provided with inclined faces 22 and thereby provide undercut or dovetail-shaped radially extending guideways for the blades. Blades H are each provided with a dovetail shaped base 23 which is adapted to fit in the groove and they are accordingly mounted for guided sliding movement toward and away from the axis of the rotor. In the particular wheel shown, blades H are also provided with beveled inner ends 2d for more sharply cutting the abrasive streams issuing from slot l5, and with flanges 2i] for preventing the abrasive from escaping over the side of the blades as it moves outwardly thereover.

The outer portions of the sides of plate I! terminate in rectangular recesses 2'5 in which the blade locking means of the invention is mounted. As previously pointed out, blades i l are mounted for free sliding movement toward and away from the axis of the machine, and the shoulder defining abutment faces i9 is cut away opposite the guideways to permit the blades to be completely removed from the apparatus. Plates l! are provided in recesses 2'! with facing, preferably semi-circular, bosses 3| which project into recesses 21. A key or looking member 32, having a depression 33 in each end corresponding to the shape of projections 3|, bridges the outer end of each guideway and abuts the outer end of each blade as illustrated in Figure 4, Base 23 of each blade I l is provided at its outer end with a cut-away portion so as to define a shoulder 35, which functions to hold key 32 in locking position when the blades are disposed in their outermost position.

The blades are installed in the apparatus by pushing them inwardly in their guideways slightly beyond their normal position so as to allow key 32 to be inserted in recesses 2?. Blades I! are then slid outwardly so as to bring their shoulders into overlapping relationship with the keys and thereby prevent inadvertent removal thereof. The blades may be pulled out into their operating position or they may be left in their inner position and the wheel started and centrifugal force employed to move them to their outer position.

When the wheel is operating the centrifugal forces exerted upon the blades cause the latter to urge keys 32 outwardly and bring their curved faces 33 into intimate wedging contact with pro- J'ections 3! of plates ll.

The blades are accordingly securely locked in place while the wheel is in operation and yet they may be readily removed by stopping the wheel, tapping the blades lightly to move them inwardly slight distance, and removing the keys from recesses 21'. In order to assist removal of keys 32 they are each provided with a beveled recess 3! in which a screw-driver may be inserted to pry the keys loose should abrasive work between the parts and bind them.

In order to further restrain keys 32 against outward movement in response to the forces exerted upon them, they are also provided with recesses 33 at each outer corner, which fits over abutment H3.

The blade guards mounted on each plate I! are identical in character and therefore only one of them will be described in detail. Projecting laterally from each plate I! is a flange 39 and it is preferably reinforced by integral webs 4|, 42 and @3, which restrain'it against flexing with respect to plate 51. Flange 39 is preferably wider than the blades, and the trailing end of the flange is provided with angular recess 44 to permit keys 32 to be removed. The body of flange 39 is preferably of cylindrical form about the center of the wheel as an axis, but its trailing end is provided with a short straight portion 45 to cause the outer surface of the flange to project a slight distance inch in most instances) beyond the outer ends of the blades, and thus protect the blade tips against breakage by rebounding particles.

The leading end of flange 39 is curved at 41 and lies closely adjacent the rear surface of blade ll, so as to preclude the entrance of abrasive between it and the blade.

When the wheel is placed in operation, the abrasive stream is directed down upon the work in the manner previously described. Any shot abrasive or particles cf the work rebounding back toward the wheel comes into contact with flange 39 and is thereby prevented from entering the space between the blades and can not be picked up by the latter. Also, should a blade break and part of it fly out of the wheel during operation, strike the casing or work and rebound toward the wheel it cannot enter the spaces between the blades and destroy the remaining blades of the wheel.

The blade guard construction just described accordingly adequately protects the blades against all extraneous objects tending to enter the spaces between blades'and yet they do not impair the accessibility of the parts because, as previously pointed out, the blades may be readily removed with the guards in place.

It has also been found that due to the streamlining effect of the guards, the wheel shows a material decrease in power consumption over the same wheel operating without guards.

The modified guard construction shown in Figures 5 and 6 differs from thatdescribed in that all 'of' the guardelements are'mounted as a unitary assembly on a cover member. With continued: reference to these figures, the blades are mounted upon rotor II) in the same manner as those previously described and in order to facilitate the disclosure only one blade has been shown in place in the machine. In these figures, however, the direction of rotation of the wheel is opposite to that shown in Figures 1 to l.

-Detachalol'y secured to the faces of plates Ha, by means of a plurality of machine screws 49, which pass through openings in plates Ila. and are threaded into rotor I5, is a cover member 5! having a plurality of flanges 52 provided thereon. Trailing ends 53 of the flanges project slightly beyond the blade tips, and curved leading edges 54 closely abut the rear sides of the blades. This form of the invention functions substantially the same way as that just described. However, through the use of cover 5| this form of invention possesses the further feature of preventing abrasive or other bodies from being introduced between the blades in an axial direction.

The guard unit may be made in any suitable manner, but as shown it comprises a flanged cup member which is cut out at four places to provide slots, and one end of the flange adjacent each slot is slit back a predetermined distance to allow curved portion 54 to be formed by bending the flanges inwardly. Portions 54 are preferably welded to the surface of the cover at 55 after they are bent into the position shown in Figure 6 so as to make the structure more rigid.

In Figure 7 I have shown a construction very similar to that shown in Figure 1 with the exception that flange 39a is formed in a separate member 56, which is secured to the face of plate Ha by means of two of the screws l8. Flanges 39a are provided with portions 45a and 41a which enables the guard to function in the same manner as the guard construction of Figures 1 to 4, inclusive.

In Figure 8 I have shown a further modified form of guard construction somewhat similar to Figure '7, wherein plate 56a is provided with a radially extending flange portion 58 which lies parallel to the surface of blade I l and further prevents abrasive from finding its Way into the interior of the wheel. Flange 59 of plate 56a is shown as having a cylindrical leading end, but if desired it may be curved as in the previously described forms of the invention.

In Figure 9 I have shown a modified form of construction which allows the wheel to be of comparatively open form and yet which guards against blade breakage through impact with rebounding abrasive.

Secured to the face of each plate l'la adjacent the advancing face of blades H by means of one of the machine screws l8, employed to hold plate I! in place, is an angular block-like member 6|. If desired, member 6| may be provided with a dowel 62 entering an aperture in plate I! to properly position it. Each block 6! is provided with a curved outer face 63 and its trailing edge 64 preferably projects beyond the end of the blade tips'so as to protect: them from rebounding abrasive in the manner previouly described.

Members 61- are also provided with inclined faces 65 forimpacting-any abrasive or other objects that may rebound into the wheel. Whenthe wheel is in operation, should abrasive or other objects find their way between blades l I and members 5! they are struck by members 65 thereby protecting blades H against injury. In view of the fact that faces 65 are inclined, or are none radial, the abrasive is given a glancing blow. Therefore, the impact of abrasive with members 5! is not nearly as great as would occur with blades Ii, which are substantially radially disposed.

In Figure 10 members 6 la are shown as mounted on plate l'la by means of one of the screws l8, and a dowel pin El, and they function in identically the same manner as those shown in Figure 9, as they are provided with correspondingly curved faces 63a and inclined faces 65a. In this instance, however, members 61a are formed of pressed metal bent up to provide flanges 68 which are welded together to provide a unitary rigid structure shown, but if desired the structure may be cast. AlthoughI have illustrated and described both the blade guard and the blade locking features of the invention as applied to a particular abrading machine and one that possesses the feature of controlling the direction of discharge of the abrasive it is to be understood that the invention is applicable to other types of abrading wheels and machines that discharge the abrasive through 360 of their periphery, and the appended claims. are intended to embrace the invention when it assumes these forms.

In some installations, where through the nature of the abrasive or other factors small quantities of abrasive may be deposited on the inner surfaces of the guards when the machine is starting up or is being shut down. In the forms of the invention shown in Figures 5 and 9 the abrasive will not remain in the wheel but will slide off of the inner faces of the guards when the wheel is started. In the other forms of the invention the abrasive has a tendency toremain on the guards and if it is non-uniformly distributed, and sufficient quantity builds up on them the wheel may become dynamically unbalanced.

If desired the operator, when encountering an operating condition of this character may sweep or blow the abrasive from the inner faces of the guards. Another way of removing this stray abrasive is to employ one or more air blast nozzles, preferably mounted on the machine and directed obliquely and outwardly against the rotor so as to pass air currents over the inner faces of the guards in a direction away from the rotor. If desired the valves for the air nozzles may be automatically operated for a predetermined time interval each time the machine is started. For instance, the valve may be operated by a solenoid in the circuit of the motor of the machine and be designed to open for a predetermined time every time the motor circuit is closed.

In Figure 11 I have shown a guard assembly similar to that illustrated in Figure 1, but the guards are so constructed as to automatically drain any abrasive that may be deposited thereon. With continued reference to this figure, guards 39 are integrally formed with plates I! as before, but they are made up of a plurality of wedge-shaped segments 10 which are disposed in spaced relationship so as to provide a plurality of drain slots 1|. Each segment 10 provides a curved outer surface whose trailing end 45 is fiattened to project slightly beyond the cylinder of revolution defined by the outer end of the blades, and whose leading end 41 is inwardly curved so as to lie adjacent the rear face of its blade ll.

With this form of the invention any abrasive that may find its way onto the inner surfaces of the guards glides off of the inclined surfaces thereof and is exhausted through openings H. Accordingly, the guards are kept clear of abrasive at all times, and yet the comparatively small radial walled slots H prevent abrasive from entering the wheel.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In an abrading apparatus, a rotor having a plurality of outwardly extending guideways provided therein, an abrasive propelling blade mounted for sliding movement in each of said guideways, and means for releasably locking'said blades against outward movement in said guideways comprising a key element bridging the outer end of each guideway and adapted to be abutted by the outer end of each blade, said rotor being provided adjacent the outer end of each guideway with a pair of projections which interfit with a pair of correspondingly shaped recesses provided in the opposite ends of each of said keys.

2. The abrading apparatus described in claim 1, wherein said rotor is provided with a pair of inwardly facing abutments adjacent each guideway and each of said keys is provided with a pair of surfaces for cooperation with said abutments.

3. In an abrading apparatus, a rotor having a plurality of outwardly extending abrasive propelling blades provided thereon, means for supplying abrasive to said blades, means for preventing rebounding abrasive from rebounding into the spaces between said blades and being impacted by the latter, comprising a curved guard member disposed between each adjacent pair of blades, and means for removing any abrasive that may be deposited upon the inner surfaces of said guard members.

4. The abrading apparatus described in claim 3, wherein said means for removing abrasive from the inner surfaces of said guards comprises a plurality of inclined walls terminating in a plurality of apertures provided in said guards.

5. The abrading apparatus described in claim 3, wherein the inner surface of said guards is made up of a plurality of outwardly converging walls which lead to a plurality of apertures in said guards and which constitute the said means for removing abrasive from the inner walls of said guards.

WM. A. ROSENBERGER. 

